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Method for preparing anisotropic NdFeB magnetic powder by directional crushing of thermally deformable magnets

An anisotropic, NdFeB technology, applied in the manufacture of inductors/transformers/magnets, magnetic materials, magnetic objects, etc., can solve problems such as damage to the main magnetic phase, transgranular fracture of magnets, limited application, etc., and achieve high residual magnetism. The effect of density, reduction of mechanical resistance, and improvement of degree of orientation

Active Publication Date: 2015-08-12
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that it is easy to cause transgranular fracture of the magnet and damage the main magnetic phase Nd. 2 Fe 14 B phase, causing it to be oxidized and decomposed to greatly increase the probability of producing the soft magnetic phase α-Fe phase (J.R.Jia, "Preparation of anisotropic NdFeB powders by crushing sintering magnets at high temperature", J.of University of Science and Technology Beijing ,2003,25(1):46-49), the magnetic properties of the obtained magnetic powder are low
When the "HD" method is used for crushing, although the intergranular fracture of the magnet can be achieved, the impact on the magnetic Nd 2 Fe 14 The damage caused by phase B, but its process requirements are high, the broken magnetic powder needs to take follow-up measures to remove the hydrogen, and the low-temperature dehydrogenation will make it difficult to remove the hydrogen in the magnetic powder, and the high-temperature dehydrogenation will lead to the microstructure of the magnetic powder. And the loss of control of the magnetic properties, which greatly limits the application of this method

Method used

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  • Method for preparing anisotropic NdFeB magnetic powder by directional crushing of thermally deformable magnets
  • Method for preparing anisotropic NdFeB magnetic powder by directional crushing of thermally deformable magnets
  • Method for preparing anisotropic NdFeB magnetic powder by directional crushing of thermally deformable magnets

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] In this example, the rapid quenching Nd 13.5 Fe 73 co 7.5 B 6 Magnetic powder is used as raw material to prepare anisotropic magnetic powder, and the process steps are as follows:

[0034] (1) Fully dense isotropic Nd 13.5 Fe 73 co 7.5 B 6 Magnet Preparation

[0035] Quenched Nd 13.5 Fe 73 co 7.5 B 6 Weigh 20g of the magnetic powder, put it into a Φ30mm hard alloy mold, apply a pressure of 4MPa at room temperature for compaction, and then put it into a vacuum induction hot press, and conduct induction hot pressing at 700°C under vacuum conditions (6Pa). The pressure is 150MPa, and the holding time is 2 minutes. After the holding time is reached, it is cooled to room temperature with the furnace to obtain fully dense isotropic Nd 13.5 Fe 73 co 7.5 B 6 A magnet whose magnetic properties are: B r =0.9T,H ci =1018kA / m, (BH) m =130kJ / m 3 , ρ=7.73g / cm 3 ;

[0036] (2) Thermal deformation anisotropy Nd 13.5 Fe 73 co 7.5 B 6 Magnet Preparation

[0037]...

Embodiment 2

[0073] In this example, the rapid quenching Nd 13.5 Fe 73 co 7.5 B 6 Magnetic powder is used as raw material to prepare anisotropic magnetic powder, and the process steps are as follows:

[0074] (1) Fully dense isotropic Nd 13.5 Fe 73 co 7.5 B 6 Magnet Preparation

[0075] Quenched Nd 13.5 Fe 73 co 7.5 B 6 Weigh 20g of the magnetic powder, put it into a Φ30mm hard alloy mold, apply a pressure of 4MPa at room temperature for compaction, and then put it into a vacuum induction hot press, and conduct induction hot pressing at 720°C under vacuum conditions (6Pa). The pressure is 150MPa, and the holding time is 4 minutes. After the holding time is reached, it is cooled to room temperature with the furnace to obtain fully dense isotropic Nd 13.5 Fe 73 co 7.5 B 6 A magnet whose magnetic properties are: B r =0.91T,H ci =1028kA / m, (BH) m =128kJ / m 3 , ρ=7.72g / cm 3 ;

[0076] (2) Thermal deformation anisotropy Nd 13.5 Fe 73 co 7.5 B 6 Magnet Preparation

[0077...

Embodiment 3

[0113] In this example, the rapid quenching Nd 13.5 Fe 80.4 Ga 0. 5B 5.6 Magnetic powder is used as raw material to prepare anisotropic magnetic powder, and the process steps are as follows:

[0114] (1) Fully dense isotropic Nd 13.5 Fe 80.4 Ga 0.5 B 5.6 Magnet Preparation

[0115] Quenched Nd 13.5 Fe 80.4 Ga 0.5 B 5.6 Weigh 20g of the magnetic powder, put it into a Φ30mm hard alloy mold, apply a pressure of 4MPa at room temperature for compaction, and then put it into a vacuum induction hot press, and conduct induction hot pressing at 700°C under vacuum conditions (6Pa). The pressure is 100MPa, and the holding time is 2 minutes. After the holding time is reached, it is cooled to room temperature with the furnace to obtain fully dense isotropic Nd 13.5 Fe 80.4 Ga 0.5 B 5.6 A magnet whose magnetic properties are: B r =0.79T,H ci =1647kA / m, (BH) m =102kJ / m 3 , ρ=7.60g / cm 3 ;

[0116] (2) Thermal deformation anisotropy Nd 13.5 Fe 80.4 Ga 0.5 B 5.6 Magnet ...

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Abstract

The invention discloses a method for preparing anisotropic neodymium iron boron magnetic powder through directionally breaking a thermal deformed magnet. The method comprises the following steps: (1) preparing a full-densification isotropic neodymium iron boron magnet; (2) preparing a thermal deformation anisotropic neodymium iron boron magnet; (3) directionally breaking the thermal deformation magnet: directionally breaking the round-cake-shaped anisotropic neodymium iron boron magnet, prepared in the step (2), by applying a symmetrical and circulating applied force along a radial direction at room temperature under the protection of argon, wherein the breaking force is 600-700MPa, so as to obtain a lamellar magnetic sheet; and (4) breaking the magnetic sheet in a regularized way: carrying out regularized breaking on the magnetic sheet prepared in the step (3) under the protection of the argon by adopting a rolling minding method, so as to obtain the anisotropic neodymium iron boron magnetic powder.

Description

technical field [0001] The invention belongs to the field of preparation of rare earth permanent magnet materials, in particular to a preparation method of anisotropic NdFeB magnetic powder. Background technique [0002] Bonded NdFeB magnet is a magnet obtained by mixing NdFeB magnetic powder with polymer resin, using methods such as molding, injection molding, extrusion or rolling to prepare the required shape and size, and curing. Because of its good dimensional accuracy, high degree of freedom in shape, and stable magnetic properties, it is widely used in information, automobile, office automation and other fields. Compared with isotropic bonded NdFeB magnets, anisotropic bonded NdFeB magnets have higher magnetic properties, which can meet the development needs of high-performance bonded magnets. However, in order to obtain high-performance anisotropic bonded NdFeB magnets, it is first necessary to obtain high-performance anisotropic NdFeB magnetic powders. [0003] The...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F41/02H01F1/057B22F9/04B22F3/16
Inventor 刘颖李军储林华陈飚蒋红刚王仁全
Owner SICHUAN UNIV
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